1. Field of the Invention
This invention pertains to removable coupling pins for use in retaining two or more machine elements in coupled relationship. In particular the coupling pins of the present invention are adapted for use with agricultural implement hitch assemblies and the like.
2. Description of the Prior Art
In implement hitch assemblies and other mechanical couplings it is common practice to provide a cylindrical pin or shaft for forming a connection between two elements. It is customary in such mechanical couplings to provide a pin or like member which is insertable in a hole in the end of the coupling shaft to prevent separation of the connected coupling members. For example, in agricultural implement hitches one or more transversely oriented shafts are provided which form a pivotal connection or coupling between an implement and the tractor draw bar linkage. The shaft is retained in connection with the tractor hitch link arm by a removable pin which is usually provided with some form of retainer to prevent unwanted ejection of the pin from a transverse hole in the end of the shaft, which ejection would result in separation of the implement or other towed vehicle from the tractor.
A number of inventions have been developed in an effort to provide a coupling pin which is strong enough to resist breaking or bending due to loads imposed thereon by the coupled hitch linkages, which is easily inserted and removed by the machine operator, but which also is provided with suitable retaining means to prevent unwanted ejection or removal. Prior art coupling pins have been provided which include a solid shank or body component and a separate retainer ring connected to the body in a number of ways. One shortcoming of prior art coupling pins has been the difficulty in providing a pin retainer which is suitably operable to prevent unwanted removal of the pin from the hitch assembly but which is also easily moved by the machine operator to provide for insertion and removal of the coupling pin at will. For example, some prior art coupling pins have retainers which are difficult to grasp and operate with a gloved hand or by a person with poor dexterity caused by previous injury or inflammation of the joints and tendons.
Furthermore, prior art coupling pins have been somewhat expensive to manufacture, and since the nature of the use of such pins results in their frequent loss and replacement it is also desirable to provide a pin which is economical and which meets substantially all of the desiderata of use and operability.